The number of persons with Parkinson Disease (PD) in the United States is expected to double by 2030 as the population ages. Importantly, this increase in the prevalence of PD will have greater impact within the Department of Veterans Affairs (VA) because the Veteran population is older than the general population and Veterans with PD are more likely than those without PD to rely solely on VA for their health care. While PD is often characterized by the motor symptoms of the disease (tremor, bradykinesia, rigidity), non-motor symptoms such as urinary symptoms correlate more closely with impaired well-being as the disease progresses. However, the impact of urinary symptoms in PD extends beyond worsened well-being. The urinary symptoms of overactive bladder (OAB), including urgency, frequency, and nocturia, with or without urinary incontinence, are the most common urinary symptoms of PD. OAB symptoms are associated with falls (a cause of increased mortality in PD), with spouse/caregiver stress, and, ultimately with institutionalization, thus it is critical that we optimize the care of urinary symptoms for Veterans with PD. Several studies suggest abnormal central nervous system processing of sensory input from bladder afferent nerves contributes to OAB symptoms in PD, possibly because of delayed recognition of bladder fullness. This mirrors findings in non-PD populations with OAB. In the non-PD OAB population, pelvic floor muscle contractions diminish bladder muscle contraction and recent evidence demonstrates that behavioral training with pelvic floor muscle exercises improves the cortical integration of bladder afferent signals. Pelvic floor muscle exercise-based behavioral therapy for OAB symptoms requires individuals to learn a motor skill and implement an adaptive behavioral strategy to delay the need to void. Because of its effectiveness compared to drug therapy, pelvic floor muscle exercise-based behavioral therapy is recommended first-line in men and women with OAB who do not have PD. However, the most recent clinical guidelines for the treatment of urinary symptoms in PD recommend treatment with anticholinergic drugs. While some anticholinergic drugs are effective in reducing symptoms of OAB, it is important to note that there is a glaring lack of an empirical evidence base to promote these drugs in the setting of PD given that they add to the anticholinergic burden of antiparkinsonian therapy, and may worsen the cognitive and autonomic burdens of the illness. Therefore, randomized controlled trials (RCTs) are needed to optimize treatment paradigms for urinary symptoms in PD. We propose a three-site, RCT conducted at the Atlanta (lead site), Birmingham and Richmond VA's to establish non-inferiority of pelvic floor muscle exercise-based behavioral therapy compared to drug therapy for OAB symptoms in adults with PD. Groups will be stratified by OAB symptom severity, PD motor symptom severity, gender, and site. We will randomize 90 participants in order to complete the study in 80 participants, assuming 85% power and a non-inferiority margin for the OAB symptom score of 15% at 12-weeks. The primary outcome measure will be urinary symptom severity as measured by the International Consultation on Incontinence Questionnaire(ICIQ)-OAB symptom score collected at 3 time points during the study: baseline, 6 weeks, and 12 weeks. Our benchmark for successful treatment will be a ? 2 point reduction in the ICIQ-OAB symptom score, which corresponds with perceived benefit in preliminary studies of behavioral therapy treatment for OAB symptoms in PD. To evaluate the primary efficacy outcome, we will utilize a random effects mixed model and adjust for baseline OAB symptom score severity. Additionally, in order to better understand central control mechanisms of bladder function, we will determine if domain-specific cognitive function impacts the response to exercise-based behavioral therapy or drug therapy for urinary symptoms. At baseline and 12 weeks, randomized participants will undergo a brief neuropsychological battery. Understanding how domain- specific cognitive function impacts response to treatment may inform new targets for rehabilitation therapy.